Optical transfer system



Dec. 13, 196

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Filed May 13, 1964 f INVENTOR.

vosmo MUR ATA BY 76 a ATTORNEY United States Patent 3,290,988 OPTICAL TRANSFER SYSTEM Yoshio Murata, 63 Omori-cho, Nishinomiya, Japan Filed May 13, 1964, Ser. No. 367,042 Claims priority, application Japan, May 18, 1963, 38/ 26,021 1 Claim. (Cl. 88-24) The present invention relates to a novel optical transfer system and, more particularly, to an improved optical transfer process in which an original pattern is optically transferred onto a sensitive copy cylinder wherein it is to be later engraved said copy cylinder with the thus transferred original pattern engraved thereon thereby becoming a printing roll which can be utilized as a printing plate, photogravure engraving plate or rotary relief printing plate, and an apparatus in which said process is carried out.

In producing a printing roll to be employed as a printing plate, for example, such a printing roll has been usually produced by the process in which an original film is wound around the peripheral surface of a cylinder on which a sensitizer has been applied and the cylinder is exposed to light, and then printed and finally fixed. However, such a prior art process has disadvantages that since the original pattern has been formed from a film such an original pattern can not be applied on the cylinder one upon another and produces seams, and that since it is, in fact, impossible to prepare such an original pattern to precise dimensions, when the original pattern is applied on the sensitive cylinder the same will not adhere closely on the copy cylinder resulting in an image having obscure areas. And of late, another process has been proposed in which an original pattern is electrically transmitted onto a copy cylinder and the thus transmitted pattern is mechanically engraved, but such a process has been found expensive since it requires a complicated and large scale apparatus.

We have previously provided an improved and economical phototype process which has eliminated disadvantages experienced in carrying out the prior art printing plate making processes as referred to above and such a process has been made publicly known in Japanese Patent No. 296,715 specification. The present invention provides a further improvement over our previously patented process which performs an optical transfer with accuracy, and a compact and economical apparatus suitable for carrying out said process.

Accordingly, an object of the present invention is to provide an optical transfer process in which said process comprises the steps of simultaneously rotating an original cylinder bearing an original pattern thereon and a copy cylinder having a sensitizer applied thereon in opposite directions and at the same angular speed by drive means so that their opposite peripheral surfaces may approach toward each other, said original cylinder and copy cylinder being mounted on the machine in parallel to and spaced from each other; and moving an illuminating means and an optical mechanism which are disposed between said two cylinders along the axes of said original and copy cylinders whereby said original pattern may be spirally scanned by said illuminating means and light reflected from the original may be projected through said optical mechanism onto said copy cylinder so as to produce a positive image thereon which looks like a mirrored replica of the original.

The present invention also includes an optical transfer apparatus suitable for carrying out said process within its scope and said apparatus comprises a main frame, an original cylinder rotationally mounted on said main frame and bearing an original pattern thereon; a copy cylinder rotationally mounted on said main frame in parallel to "ice said original cylinder and having a sensitizer applied thereon; drive means for simultaneously rotating said two cylinders in opposite directions and at the same angular speed so that their opposite peripheral surfaces may approach toward each other; an illuminating means disposed between said two cylinders for illuminating said original on the original cylinder; and an optical mechanism disposed between said two cylinders adjacent to said illuminating means for passing a reflected light from said i1- luminating means therethrough and producing a positive image which represents a precise and symmetrical replica of said original pattern on the original cylinder.

The above and other objects and advantages of the present invention will be more readily apparent from the following description when read in connection with the accompanying drawings in which a preferred apparatus suitable for carrying out the process according to the present invention is illustrated, in which:

FIG. 1 is a top plane view of an optical transfer apparatus in which the process of the present invention is carried out;

FIG. 2 is a cross-sectional view taken substantially along the line CD of FIG. 1; and

FIG. 3 is an enlarged fragmentary view showing the optical mechanism of said apparatus.

Turning now to FIGS. 1 and 2 of the drawings, there is shown an optical transfer apparatus embodying the present invention. As shown in these figures, the apparatus comprises a main frame, an original cylinder I hearing original pattern thereon and a copy cylinder 2 having a sensitizer applied thereon. The original cylinder 1 and copy cylinder 2 are mounted in parallel to and spaced from each other on the machine frame. These original and copy cylinders 1 and 2 are driven in the opposite directions and at the same angular speed by synchronous motors 8 and 9, respectively so that their opposite peripheral surfaces may approach toward each other as indicated by the arrows in FIG. 2. An optical mechanism and an illuminating means 13 are disposed between the original cylinder 1 and copy cylinder 2. The optical mechanism comprises a first lens 3, a second lens 4 and a Dach Wollaston prism 5 and is adapted to produce a positive image on said copy cylinder or an image which represents a mirrored replica of the original pattern on the original cylinder 1. The first and second lenses 3 and 4 and prism 5 are supported by a metallic support member 11. The optical mechanism and illuminating means 13 are adapted to slidingly move along the axes of the cylinders 1 and 2 by means of a lead screw 14 which is driven from a motor 15 through a reduction gear 16. The illuminating means may be any common type which projects a focused light, and according to the present invention, the illuminating means is adapted to shed a focused light on selected areas of the original pattern which are to be optically transferred.

Therefore, when this optical apparatus is actuated by any suitable drive means the two cylinders 1 and 2 are caused to rotate and at the same time the illuminating means 13 and optical mechanism move along the axes of the two cylinders, and, accordingly, the original is illuminated by illuminating means 13 so as to be spirally scanned and the light reflected from the original is progressively projected through the optical mechanism onto the sensitizer applied to copy cylinder 2 by an amount corresponding to the width of the slit of the optical mechanism and printed thereon.

The sensitizer to be applied to copy cylinder 2 may be any wet type photographic sensitizer which includes a bichromate sensitiber such as glue, silver halide photographic emulsion, diaZo-type sensitizer, cinnamic aldehyde photographic sensitizer, or alternately, it may be any dry-type photographic sensitizer commonly employed in electronic photography. It is only necessary that the sensitizer employed in the present invention have the capability of forming an antierosive film on the copy cylinder and such a sensitizer may be applied on the copy cylinder surface in a single layer or a plurality of layers, as desired. In the present invention the sensitizer is continuously employed, so when a sensitizer suitable for electronic photography is used, it is necessary to take into consideration the degeneration in photosensitivity of the dry-type sensitizer, so a charging device and a developing device are preferably provided along the outer peripheral surface of the copy cylinder and furthermore, these devices are preferably designed to move in synchronism with the optical mechanism.

The copy cylinder 2 to which has a dry-type sensitizer has been applied is preferably disposed within a casing 10 which constitutes a camera box and shields the sensitizer from the light. The shielding casing 10 is formed with a slit means 12 which is adapted to provide a slit along the full length of the copy cylinder 2 only at the area which faces the optical mechanism.

The optical mechanism which projects the light reflected from the original onto the copy cylinder should be so designed that the mechanism can produce a positive image which represents a mirrored replica of the original pattern having the same dimensions as, but symmetric to the original pattern. Such an optical mechanism can be easily obtained by arranging a group of any suitable lenses in a proper way, but such an optical mechanism preferably comprises lenses 3 and 4 and a Dach Wollaston prism 5 as is more clearly shown in FIG. 3, since they can be easily brought into focus and can effectively prevent the loss of incident light.

With an optical mechanism arranged as shown in FIG. 3, the light reflected from original cylinder 1 is inverted .by prism 5 and projected through lenses 3 and 4 onto copy cylinder 2 to produce a positive image thereon. In such a system the light which has passed through prism 5 is received by the first lens 3 maintaining its original shape and dimensions and in this lens the light is changed into a horizontal line and is received by the second lens 4 and then projected onto the copy cylinder 2 minimizing the loss of light. In addition, lenses 3 and 4 can be easily brought into focus by adjusting the distance between these two lenses. The pattern e as indicated by the arrow direction E is symmetrically projected as the pattern 1 as indicated by the arrow direction F as shown in FIG. 3. When a printing plate bearing such a pattern engraved thereon is employed for printing purposes, the surface of the printed product will have a pattern corresponding precisely to the pattern 2.

In producing a printing roll, generally, a pattern which extends somewhat far in the peripheral direction of a cylinder as compared with the original pattern is required.

When using the present invention, an extended pattern such as is referred to above, can be obtained by using the formula right angles to the axis of the copy cylinder. For attaining the above purpose, if cylindrical lenses are arranged to form a zoom lens system, the value of d can be optionally selected.

The driving means for the optical transfer apparatus may be of any suitable type provided that such a driving means is appropriate for carrying out the present invention, and therefore, the synchronous motor or the synchronous motor and lead screw assembly as shown in FIGS. 1 and 2 are only illustrative. The same can be also applied to the other parts of the apparatus as illustrated.

According to the present invention, even if the original pattern wound around the original cylinder becomes more or less baggy or uneven thereon, as long as such bagginess or unevenness is small and remains within the depth of focus of the optical mechanism, the transferred image is clear and free of any obscure areas, and since the original pattern can be attached to a sheet of printing paper or drawing paper at its both ends in an overlapping relation therewith, the reflected pattern can be exactly positioned on the copy cylinder. Furthermore, the direction of the light source can be optionally selected, so almost no seams will show on the copy cylinder. The present invention also eliminates the difficulties referred to above in connection with the extension of the pattern and makes it possible to enlarge or reduce the pattern dimensions as desired. Moreover, according to the present invention, since the sliding portions of the apparatus are only the illuminating means and optical mechanism, the size of the apparatus employed for carrying out the present process is smaller and the construction is simpler as compared with that shown in the above-mentioned Japanese Patent No. 296,715 and a more accurate optical transfer operation can be achieved.

While only one embodiment of the present invention has been shown and described in detail it will be understood that the same is for the purpose of illustration only and is not to be taken as a definition of the scope of the present invention, reference being had for this purpose to the appended claims.

What is claimed is:

An optical apparatus comprising a main frame; an original cylinder rotationally mounted on said main frame and bearing an original pattern thereon; a copy cylinder rotationally mounted on said main frame in parallel to said original cylinder and having a sensitizer applied thereon; drive means for simultaneously rotating said two cylinders in opposite directions and at the same angular speed so that their opposite peripheral surfaces may approach toward each other; an illuminating means disposed between said two cylinders for illuminating and spirally scanning said original pattern on the original cylinder; and an optical mechanism disposed between said two cylinders adjacent to said illuminating means for passing the reflected light from said illuminating means therethrough and producing a positive image which looks like a mirrored replica of the original pattern on said original cylinder, said optical mechanism including a group of lenses and a Dach prism located in front of said group of lenses.

References Cited by the Examiner UNITED STATES PATENTS 3,216,316 11/1965 Brownscombe 88-24 NORTON ANSHER, Primary Examiner.

RICHARD A. WINTERCORN, Assistant Examiner. 

